Melanoma Mitotic Rate — SCE Dermatology MCQ

Correct answer: A — Higher mitotic rate correlates with more aggressive biological behaviour, worse prognosis, and was previously used in AJCC staging (7th edition) to substage T1 melanomas; it remains an important prognostic factor

Option A is correct: higher mitotic rate correlates with more aggressive biological behaviour, worse prognosis, and was previously used in AJCC staging (7th edition) to substage T1 melanomas; it remains an important prognostic factor. Mitotic rate (mitoses per mm2 in the dermal component) reflects proliferative activity of the tumour, and increasing counts are independently associated with reduced melanoma-specific survival. In AJCC 7th edition, a mitotic rate of at least 1/mm2 defined T1b disease; the 8th edition replaced this with a 0.8 mm thickness threshold plus ulceration for T1 substaging, but mitotic rate is still recorded on every melanoma histology report because of its ongoing prognostic value and its use in some centres when weighing sentinel lymph node biopsy decisions in thin melanomas. A rate of 5/mm2, as in this case, denotes a proliferatively active tumour and signals a less favourable outlook regardless of the staging edition applied.

Reference: https://www.nice.org.uk/guidance/conditions-and-diseases/skin-conditions